Blow-molded polyethylene containers may be produced using low-density (i.e., density below 0.94 g/cc) polyethylene resins (LDPE). Typically the density of these resins is about 0.92 g/cc and these resins have a broad molecular weight distribution (MWD). These containers have a soft feel, are quite pliable (i.e., squeezable) and can be easily grasped by young children. Presently, however, recycling systems for LDPE containers are not widely available.
Blow-molded polyethylene containers may also be produced using high-density polyethylene resins (HDPE) (i.e., having a density of 0.94 or greater) having a melt index of less than 1.0. These HDPE containers, although readily recyclable, have a stiff feel and are not desirable for use with small, hand-held containers, such as single-serving, squeezable beverage containers.
It would be desirable to have a blow-molding resin that is, for purposes of recyclability, a high-density polyethylene and yet will produce a single-serving sized beverage container that is soft and flexible. Further, it would be desirable if such resins enabled easy trimming of flash from the molded pieces even with the use of blow-molding machines having limited clamping force, such as about 500 kg (less than 1.0 ton). Still further, it would be desirable if these resins enabled the use of the easy twist-off opening features which are commonly incorporated in one-piece, blow-molded, single-serving beverage containers. These opening features desirably separate when rotated less than 90.degree. using a force of about one pound or less
Blow-molded beverage containers of the type shown in U.S. Pat. Nos. 5,280,844 to Kaufman et al., U.S. Pat. No. 5,188,250 to Kovacic et al. and U.S. Pat. No. 5,076,452 to Hashimoto et al., all of which are hereby incorporated by reference, are examples of containers which have twist-off opening features and which may be advantageously produced with the blow-molding resins of this invention.